Owls & iPods

Owls & iPods: Great Horned Owl and Chick, Courtesy US FWS Digital Library, George Gentry Photographer
Great Horned Owl and Chick
Photographer: George Gentry
US FWS Digital Library

Hi I’m Holly Strand.

In early spring, my friends and I went owling in a northern Utah canyon. We were hoping for modest success—just to see or hear a northern pygmy or great horned owl — both common owls in our area.

To better the odds we brought an iPod with prerecorded owl sounds. We played the northern pygmy call for 20-30 second intervals and listened intently in between intervals.

After 10 minutes of off-and-on playbacks we heard an answering call from a nearby conifer grove. We were ecstatic that we had made contact with an actual owl. But wait! Was it an owl we heard or just another iPod user?

Pygmy Owl, Courtesy US FWS Digital Library, Bob Miles Photographer
Pygmy Owl
Photographer: Bob Miles
US FWS Digital Library

According to David Sibley, author of the Sibley Guide to Birds, the proliferation of digital audio devices and recorders among birders has both pluses and minuses. On the plus side, you can often entice certain birds out of hiding using playbacks. For example, if a territorial male thinks a rival bird is threatening to encroach on its territory, he may come out to confront the intruder. Or he may sing his “I’m Here, So Stay Away” song. A female bird might approach the recording source as a potential date. Using playbacks, you can target specific species to see or hear without disturbing others.

On the flip side, overuse of these playback devices can cause unnecessary stress and distraction in the target birds—and annoyance among other birders. In one study, the use of playbacks upset the avian apple cart by causing high-ranking black- capped chickadee males to lose status. The rest of the flock perceived them as losers as they were unable to drive away an unwanted phantom intruder.

Because the widespread use of recorded playbacks is relatively new, proper etiquette is still evolving. But here are some key points.

  • Keep the volume low and use only occasional snippets of sound—less than 30 seconds at a time. Leave a long pause between snippets. Definitely do not broadcast loud or continuous sound.
  • It is illegal to disturb endangered or threatened species. And these recordings can be interpreted as disturbance. So stick with sounds of non-threatened species.
  • Finally, check the rules at your birding location. The use of playback is prohibited in some parks and refuges.

For source material and websites with bird sound recordings, go to www.wildaboututah.org.

For Wild About Utah, I’m Holly Strand.

Credits:

Photos: Courtesy US FSW Digital Media Library
Text: Holly Strand

Sources & Additional Reading:

Sibley, David. 2011. The Proper Use of Playback in Birding. Sibley Guides: Identification of North American birds and trees. https://www.sibleyguides.com/2011/04/the-proper-use-of-playback-in-birding/ [Accessed May 19, 2011]

Recordings:

Soundscapes for Birders by Kevin Colver

https://www.xeno-canto.org/ shared bird sounds from the whole world

Beletsky, Les, editor. 2010. Bird Songs Bible: The Complete, Illustrated Reference for North American Birds Contains digital audio player.

Ipods and mp3 apps:

iBird https://www.ibirdexplorer.com

Audubon Birds Field Guide https://www.audubonguides.com/field-guides/mobile-apps.html

The Sibley eGuide to the Birds of North America https://www.mydigitalearth.com

Owls: Silent Hunters

Barn owl sleeping in a tree, Photo Copyright 2010 Mike Fish
Barn Owl Sleeping in a Tree
Copyright © 2010 Mike Fish

Great Horned Owl  Photographer: Ronald Laubenstein US FWS Digital Library Great Horned Owl
Photographer: Ronald Laubenstein
US FWS Digital Library

Click for a larger image - Western Screech Owl courtesy and copyright 2007 Lu Giddings Western Screech Owl
Copyright © 2007 Lu Giddings

Click for a larger view of the tethered Snowy Owl, Bubo scandiacus, Image courtesy US FWS.  Ronald Laubenstein, Photographer Tethered Snowy Owl in Alaska
Bubo scandiacus

Courtesy US FWS
Ronald Laubenstein, Photographer

Click for a larger view of Snowy Owl in Alaska, Bubo scandiacus, Photo taken in Alaska by Floyd Davidson, Photographer, Courtesy Wikimedia and licensed through GNU Free Documentation License 1.2Snowy Owl in Alaska
Bubo scandiacus

Courtesy Wikimedia
Floyd Davidson, Photographer
Licensed under the
Creative Commons: GNU Free Documentation License

Click for a larger view of Snowy Owl with chick, Bubo scandiacus, Photo taken by Tony Hisgett, Photographer, Courtesy Wikimedia and licensed through the Creative Commons: Attribution 2.0 Generic LicenseSnowy Owl with Chick
Bubo scandiacus

Courtesy Wikimedia
Tony Hisgett, Photographer
Licensed under the
Creative Commons: Attribution 2.0 Generic License

Click for a larger view of Snowy Owl in Alaska, Bubo scandiacus, Photo taken by Bert de Tilly, Photographer, Courtesy Wikimedia and licensed through the Creative Commons: Attribution-Share Alike 3.0 Unported LicenseSnowy Owl in Flight
Bubo scandiacus

Courtesy Wikimedia
Bert de Tilly, Photographer
Licensed under the
Creative Commons: Attribution-Share Alike 3.0 Unported License

Hi, this is Mark Larese-Casanova from the Utah Master Naturalist Program at Utah State University Extension.

Walking across the yard late at night, the crescent moon was casting little light. A dark, phantom shape soared past our heads. It was silent, not making a single noise. It could only be one thing out here in the night- an owl, drifting off into the darkness.

Even though they hunt at night, owls use their vision to find prey. Owl eyes are proportionately large compared to those of other birds, and also have large corneas and pupils to allow more light into the eye. The retina, where an image is formed at the back of the eye, is so large that an owl’s eye is shaped more like a rounded cone or tube rather than a ball. Because the back of an owl’s eye is wider than the front, owls cannot move their eyes within the socket like other animals. To make up for this, owls are able to turn their heads three-quarters of a full rotation!

To supplement its acute vision, owl’s ears are particularly well adapted for hearing prey. In fact, some owls hear so well that they can catch prey in complete darkness. The feathers of the facial disk- the round, flat areas around the eyes- help direct sound toward their large ear openings. In addition, an owl’s ear openings are set relatively far apart on its skull, and at different orientations on each side. One is high and more forward on the skull, and the other is lower and to the rear. This allows owls to locate noises, such as the rustling of a mouse, by triangulation with remarkable precision.

Excellent sight and hearing are helpful to owls, but very quiet feathers help them sneak up on prey. Relatively large wings covered with feathers that have a velvety soft upper surface and a serrated edge reduce noise during flight. Owls even have feathers on their legs to help keep quiet!

Most birds sleep soundly in their roosts at night. But, it’s not uncommon for us to see an owl gliding through the darkness in search of its prey. Just don’t expect to hear them…

For Wild About Utah, I’m Mark Larese-Casanova.

Credits:
Images: Courtesy US FWS images.fws.gov
Courtesy and Copyright Mike Fish
Courtesy and Copyright Lu Giddings
Courtesy Wikimedia & licensed through CCL
Text:     Mark Larese-Casanova, Utah Master Naturalist Program
            at Utah State University Extension.


Additional Reading:

Berger, C. (2005). Owls. Mechanicsburg, PA: Stackpole Books.

Lynch, W. (2007). Owls of the United States and Canada. Baltimore, MD: Johns Hopkins University Press.

Owl Feathers and Flight. (2012). In The Owl Pages. Retrieved September 20, 2013, from https://www.owlpages.com/articles.php?section=owl+physiology&title=Feathers

Owl Eyes and Vision. (2012). In The Owl Pages. Retrieved September 20, 2013, from https://www.owlpages.com/articles.php?section=owl+physiology&title=Vision

Owls and iPods

Great Horned Owl and Chick, Courtesy US FWS Digital Library, George Gentry Photographer
Great Horned Owl and Chick
Photographer: George Gentry
US FWS Digital Library

Hi I’m Holly Strand.

In early spring, my friends and I went owling in a northern Utah canyon. We were hoping for modest success—just to see or hear a northern pygmy or great horned owl — both common owls in our area.

To better the odds we brought an iPod with prerecorded owl sounds. We played the northern pygmy call for 20-30 second intervals and listened intently in between intervals.

After 10 minutes of off-and-on playbacks we heard an answering call from a nearby conifer grove. We were ecstatic that we had made contact with an actual owl. But wait! Was it an owl we heard or just another iPod user?

Pygmy Owl, Courtesy US FWS Digital Library, Bob Miles Photographer
Pygmy Owl
Photographer: Bob Miles
US FWS Digital Library

According to David Sibley, author of the Sibley Guide to Birds, the proliferation of digital audio devices and recorders among birders has both pluses and minuses. On the plus side, you can often entice certain birds out of hiding using playbacks. For example, if a territorial male thinks a rival bird is threatening to encroach on its territory, he may come out to confront the intruder. Or he may sing his “I’m Here, So Stay Away” song. A female bird might approach the recording source as a potential date. Using playbacks, you can target specific species to see or hear without disturbing others.

On the flip side, overuse of these playback devices can cause unnecessary stress and distraction in the target birds—and annoyance among other birders. In one study, the use of playbacks upset the avian apple cart by causing high-ranking black- capped chickadee males to lose status. The rest of the flock perceived them as losers as they were unable to drive away an unwanted phantom intruder.

Because the widespread use of recorded playbacks is relatively new, proper etiquette is still evolving. But here are some key points.

  • Keep the volume low and use only occasional snippets of sound—less than 30 seconds at a time. Leave a long pause between snippets. Definitely do not broadcast loud or continuous sound.
  • It is illegal to disturb endangered or threatened species. And these recordings can be interpreted as disturbance. So stick with sounds of non-threatened species.
  • Finally, check the rules at your birding location. The use of playback is prohibited in some parks and refuges.

For source material and websites with bird sound recordings, go to www.wildaboututah.org.

For Wild About Utah, I’m Holly Strand.

Credits:

Photos: Courtesy US FSW Digital Media Library
Text: Holly Strand

Sources & Additional Reading:

Sibley, David. 2011. The Proper Use of Playback in Birding. Sibley Guides: Identification of North American birds and trees. https://www.sibleyguides.com/2011/04/the-proper-use-of-playback-in-birding/ [Accessed May 19, 2011]

Recordings:

Soundscapes for Birders by Kevin Colver https://wildstore.wildsanctuary.com/collections/special-collections

https://www.xeno-canto.org/ shared bird sounds from the whole world

Beletsky, Les, editor. 2010. Bird Songs Bible: The Complete, Illustrated Reference for North American Birds Contains digital audio player.

Ipods and mp3 apps:

iBird https://www.ibirdexplorer.com

Audubon Birds Field Guide https://www.audubonguides.com/field-guides/mobile-apps.html

The Sibley eGuide to the Birds of North America https://www.mydigitalearth.com

Owl Vision

Barn Owl Sleeping in a Tree
Copyright © 2010 Mike Fish

Hi I’m Holly Strand.

Great-horned and other nocturnal owls have phenomenal nighttime vision. In some respects—they see much better by night than we can by the light of the sun. The visual acuity of owls springs from a number of interesting adaptations.

Of course you’ve noticed that owls have big eyes. If our eyes were in the same proportion to the size of our head, they would be the size of grapefruits! Large owl corneas and lenses help maximize the amount of light received by the retina.

There are two types of photo receptors in the retina. Cones operate in bright light and give fine detail and color vision. Rods work with much less light but compromise somewhat on detail and color. Owl eyes contain considerably more rods than cones while the eyes of daytime animals–like us –contain many more cones than rods.

Great Horned Owl
Copyright © 2010 Mike Fish

Owls –and other nocturnal creatures—have a mirror-like structure behind the retina called a tapetum. Light passes through the rods and cones, strikes the tapetum and is reflected back through the eye to the light source. The tapetum ensures that any light unabsorbed by receptor cells is reflected back through the eye. This gives the receptor cells a second chance at stimulating the rods.

Owls, like most predators, have eyes positioned forward on the face and looking in the same direction. The resulting binocular vision gives the owl a three dimensional perspective. By accurately sensing depth, the owl can zero in on a tasty little mouse scurrying across a field and make adjustments on the wing as it closes in for a kill. To help triangulate even more precisely, owls will often bob or weave their heads to get several viewpoints of an object.

Finally, because of their unique eye structure, owls cannot move their eyes within the sockets. No worries! The owl just moves its whole head instead. On an exceptionally mobile neck, an owl head can rotate at least 270 degrees from side to side and 90 degrees up and down.

For some great pictures of owls and their enigmatic eyes, go to www.wildaboututah.org

For Wild About Utah, I’m Holly Strand.

Credits:

Photos: Courtesy and Copyright 2010 Mike Fish

Text: Holly Strand

Sources & Additional Reading:

Cornell Lab of Ornithology. https://www.birds.cornell.edu/

Utah Division of Wildlife Resources. Utah Conservation Data Center. https://dwrcdc.nr.utah.gov/ucdc/

Scholz, Floyd. 2001. Owls. Mechanicsburg PA: Stackpole Books

Sparks, John and Tony Soper. 1989. Owls: Their Natural and Unnatural History. NY: Facts on File.